Picture came through fine. That is where BOSS unit is located.
I do know Coachmen changed configurations multiple times during production due to supply issues. The next thing I would do is remove the outside TV and see if there are RCA cables going back into the coach form it. If so, follow those cables under the sink and see where they go. If no cables, maybe the speakers are powered off of the dash radio or a radio somewhere else in the coach.
Sorry I am not much more help with that. If you were near Austin I would pop by and find it for you